Stent system deployment method for bifurcated lesion

ABSTRACT

A deployment apparatus and method for deploying one or more stents to a bifurcated vessel is provided. The invention is particularly suited for T-type bifurcated vessels where a side branch extends from a main branch. The deployment apparatus has a primary inflatable portion for engagement within the main branch and a secondary inflatable portion for engagement within the side branch. A main stent is arranged on the primary inflatable portion and radially expanded within the main branch while the secondary inflatable portion maintains registration with the side branch. A side branch stent is then arranged on the secondary inflatable portion and expanded within the side branch while the primary inflatable portion maintains registration with the expanded main stent. A bifurcated stent system suitable for bifurcated lesions is also provided comprising a side branch stent with a shaped end designed to engage a similarly shaped side opening in a main stent.

The present application is a divisional of U.S. application Ser. No.15/274,766, filed Sep. 23, 2016, issued as U.S. Pat. No. ______, whichis a divisional of U.S. application Ser. No. 14/239,611, filed Feb. 24,2014, issued as U.S. Pat. No. 9,486,342, which is a U.S. nationalcounterpart application of international application no.PCT/CA2012/000771, filed Aug. 20, 2012, which claims the benefit, under35 U.S.C. § 119(e), of U.S. Provisional Application No. 61/525,627,filed Aug. 19, 2011, each of which is hereby incorporated by referenceherein in its entirety.

FIELD OF THE INVENTION

The present invention relates to a deployment apparatus and method fordeploying one or more stents to a bifurcated vessel. The deploymentapparatus is particularly suited for bifurcated vessels of the typecomprising a main branch from which a side branch extends therefrom. Theinvention is also related to a bifurcated stent system suitable for usein bifurcated vessels.

BACKGROUND OF THE INVENTION

The term stent has been used interchangeably with terms such asintraluminal vascular graft and expansible prosthesis. As usedthroughout this specification, the term stent is intended to have abroad meaning and encompasses any expandable prosthetic device forimplantation in a body passageway (e.g. a lumen or artery).

There have been various attempts at addressing the delivery anddeployment of stents at bifurcated lesions. Bifurcated vessels may be ofthe Y-type, wherein a main branch bifurcates into two secondarybranches, or of the T-type, wherein a side branch extends from a mainbranch. While the subject invention may be employed in certaincircumstances with Y-type bifurcated vessels, it is primarily directedfor use with T-type bifurcated vessels.

One common approach is to place a conventional stent in the main largerbody lumen over the origin of the side branch. After removal of thestent delivery balloon, a second wire is introduced through a cell inthe wall of the deployed stent and into the side branch. A balloon isthen introduced into the side branch and inflated to enlarge that cellof the main vessel stent. A second stent is then introduced through theenlarged cell into the side branch and expanded therein.

Another strategy employed is the kissing balloon technique, in whichseparate balloons are positioned in the main and the side branch vesselsand simultaneously inflated. Various two stent approaches includingCulotte, T-stent and crush stent techniques have been employed as wellas described in detail in U.S. Pat. No. 7,481,834 to Kaplan et al.

One of the drawbacks of the conventional stent techniques is that theyrun the risk of compromising the degree of the patency of the primaryvessel and/or its branches or bifurcation. This may occur as a result ofseveral problems, such as displacing disease tissue, vessel spasm, anddissection with or without intimal flaps, thrombosis, and embolism, thatwill increase the chance of restenosis.

These limitations have led others to develop specifically designedstents to treat bifurcation lesions. One approach employs a stent designwith a side opening: U.S. Pat. Nos. 6,325,826 and 6,210,429 to Vardi etal.; U.S. Pat. No. 6,033,435 to Penn et al.; U.S. Pat. No. 6,056,775 toBorghi et al. A second approach includes a distal bifurcation of thestent: U.S. Pat. No. 4,994,071 to MacGregor; and U.S. Pat. No. 6,740,113to Vrba. A third approach is having at least two axially alignedcircumferential anchors: U.S. Pat. No. 7,481,834 to Kaplan et al.

Though these approaches have many theoretical advantages, they haveshortcomings in:

(a) Accurate positioning of the stent in the main vessel and the sidebranched or bifurcated lesion;

(b) Adequate stent coverage which will result in high chance ofrestenosis;

(c) Prevention of over-stretching of the proximal main artery whendouble balloons are used, as in the kissing balloon technique, which candamage the artery and increase the risk of restenosis in the stent;

(d) Prevention of high metal to artery ratio resulted from crushing thestruts of the main stent, in order to make an opening to access the sidebranch artery for deployment of the side branch stent, which increasesfluid turbulence that may result in deposition of clot material whichcan cause blockage at the site of the bifurcation of the stent;

(e) Prevention of the plaque shifting in the bifurcated arteries duringballoon inflation;

(f) In the case of the Kaplan et al. U.S. Pat. No. 7,481,834, insertionof traditional stent into a main vessel, after deployment of the newdesign stent in the side branched stent with anchor design, may pose alimitation to blood flow and access to the side branch vessel. The term“stent j ail” is often used to describe this concept.

Another drawback is with the balloon delivery system that assists inpositioning the stent with accuracy in the bifurcated lesions,particularly involved in the procedure of double balloon sequentialdilation for the stent, which has not proven to be very successful.These limitations have led others to develop specifically designedballoons to treat bifurcation lesions, such as in U.S. Pat. No.6,017,324 to Tu et al. This design has its limitations in that it willhelp to solve specific bifurcation lesions when the distal branches havea Y-shape and the size of the distal vessels are smaller than the sizeof the proximal vessel (e.g. the aortic artery at bifurcation with iliacarteries) but it is not suitable if the size of one of the distalbranches is equal to the proximal vessel size, and not suitable for theside branched vessels which are the majority of the cases.

Accordingly, there is a need for an improved stent design and deliveryballoon apparatus and method of deployment, most particularly forapplication within the cardiac, coronary, renal, peripheral vascular,gastrointestinal, pulmonary, urinary and neurovascular system, and thebrain, which:

(1) Provides for a proper balloon stent delivery system and method forhigh accuracy for deployment of the stent in branched or bifurcatedlesions;

(2) Completely covers the bifurcation point of the bifurcation vesselswith a high degree of accuracy;

(3) Provides a proper balloon delivery system that will preventoverstretching of the proximal part of the main artery even where twoballoons used as kissing balloons;

(4) Prevents high metal to artery ratio at the bifurcation junction, bypreventing crushing the struts of the main stent, in order to create anopening in the main stent to access the side branch artery;

(5) Prevents the plaque shifting in the bifurcated arteries duringballoon inflation;

(6) Allows for differential sizing of the stents in bifurcated stentapparatus even after the main stent is implanted; and

(7) Is usable to treat bifurcated vessels where the branch vesselextends from the side of the main vessel.

SUMMARY OF THE INVENTION

These and other disadvantages of the prior art are overcome by providingan inflatable deployment apparatus which has an inflatable side branchportion adapted to engage the side branch and maintain registrationtherewith. A method for deployment of one or more stents to a bifurcatedvessel is also provided as is a stent system with a novel design thatallows accurate placement thereof at the bifurcated junction.

In general, it is desirable to provide a branched balloon catheter, forperforming balloon dilatation procedures in body lumen, particularly atbifurcated junctions. It is also desirable to provide a balloon catheterhaving branched portion adapted to engage a side branch of a bifurcatedvessel. The “branched balloon” of this invention is also referred to asan inflatable apparatus having a main branch portion, with proximal anddistal ends, wherein the branched portion originates from a mid-regionthe side of the main branch portion, preferably about mid-distancebetween the proximal and distal ends, and extends outwardly therefrom,preferable at an angle of between about 10 and 170° relative to the mainbranch portion.

The term “vessel” as used herein generally means a tubular tissue withinthe cardiac, coronary, renal, peripheral vascular, gastrointestinal,pulmonary, urinary and neurovascular systems and brain.

It is also desirable to provide a branched deployment apparatus balloonusing over the wire means, wherein the wire means has a proximal end andtwo-head distal sections with two distal ends, one at the distal end ofthe main branch portion, and the second at the distal end at thebranched portion. Alternately, the guide wire means may comprise twowires, each wire having its own distal end, and its own proximal end,wherein each wire is independently controllable.

It is also desirable to provide a method and a stented branched deliverycatheter for treating stenosis or blocked vessels at the bifurcationregion of the vascular vessel by precisely deploying the stent in place.

The inflatable “balloon” portions referred to herein are generallyincluded within two broad classes. One class is considerednon-compliant, and are formed from a generally non-stretchable materialsuch as polyethylene, polyethylene terephthalate, polypropylene,cross-liked polyethylene, polyimide, and the like. The other class isconsidered compliant, formed from a generally compliant or stretchablematerial such as nylon, silicon, latex, polyurethane and the like.

While the inflatable portions can be unitary and contiguous, it wouldalso be desirable to provide a deployment system which uses dualballoons, which are connectable to a common or separate supply of gas orfluid for inflation. By permitting inflation of the main branch portionand side branch portion with a single inflator/deflator device,identical inflation of both portions can be effected at the same time,which will reduce the shifting of the plaque inside the bifurcatedcoronary arteries.

The use of two balloons may provide for easier manufacture than aunitary and contiguous inflatable system, however, issues also arisewith the use of two balloons as overlapping sections tend not to behavein the same manner upon expansion as non-overlapping sections. It wouldtherefore be desirable to provide a restriction mechanism to moderateand control expansion of overlapping sections. Such a restrictionmechanism may take the form of a sleeve which envelops the overlappingsections. The sleeve may assume a balloon like function which expandsunder inflation and collapses under deflation.

The invention described herein satisfies one or more of these desires.In particular, there is provided in accordance with one aspect of theinvention an inflatable apparatus for deploying at least one stent in abifurcated vessel having a main branch from which a side branch extendstherefrom, comprising a primary inflatable portion having proximal anddistal ends, and a secondary inflatable portion extending away from aregion between the proximal and distal ends of the primary inflatableportion. The primary inflatable portion is positionable within the mainbranch and the secondary inflatable portion positionable within the sidebranch such that when the primary and secondary inflatable portions areinflated, the primary inflatable portion expands radially in the mainbranch while the secondary inflatable portion maintains registrationwith the side branch by expanding radially therein.

The primary and secondary inflatable portions may be contiguous.Alternately, the inflatable deployment apparatus may comprise a firstballoon and a second balloon each having proximal and distal ends. Asleeve may be provided that surrounds the overlapping sections of theballoons. The distal end of the second balloon forms the secondaryinflatable portion while the sleeve-surrounded proximal overlapping endsand the distal end of said first balloon form the primary inflatableportion. The sleeve is designed to restrict the expansion of theproximal overlapping ends of the balloons to the same extent as theexpansion of the distal end of the first balloon so as to provide arelatively uniform expansion of the so-called main branch portion.

According to another aspect of the invention, there is provided a methodfor deployment of at least one stent in a bifurcated vessel having amain branch from which a side branch extends therefrom, comprising:

providing an inflatable apparatus having a primary inflatable portionand a secondary inflatable portion;

arranging a first stent on the primary inflatable portion;

deploying the inflatable apparatus to the site of the bifurcated vesseland positioning the primary inflatable in the main branch and thesecondary inflatable portion in the side branch;

inflating the primary and secondary inflatable portions so as to causethe first stent to radially expand within the main branch while thesecondary inflatable portion maintains registration with the sidebranch.

The method may further comprise positioning the secondary inflatableportion through an opening in the first stent when arranging the firststent on the primary inflatable portion.

The method may further comprise removing the inflatable apparatus oncethe first stent has been expanded;

arranging a second stent on the secondary inflatable portion;

redeploying the inflatable apparatus by positioning the primaryinflation portion within the expanded first stent and positioning thesecondary inflatable apparatus in the side branch;

inflating the primary and secondary inflatable portions so as to causethe second stent to expand radially within the side branch while theprimary inflatable portion maintains registration with the main branch.

The second stent may further comprise alignment means for orienting theproximal end of said second stent with the opening of said first stent.

According to a further aspect of the invention, there is provided astent system for a bifurcated vessel having a main branch from which aside branch extends therefrom, comprising:

a first radially expandable stent for supporting the walls of the mainbranch; and

a second radially expandable stent for supporting the walls of the sidebranch;

the second stent having a shaped proximal end;

the first stent having an opening in a side wall thereof, the openinghaving a shape which engages with the shaped proximal end of the secondstent upon expansion.

The second stent may further comprise alignment means for orienting theproximal end of the second stent with the opening of the first stent.

The alignment means may comprise an expandable alignment brace extendingfrom the proximal end of the second stent. The alignment brace ispositionable though the opening in the first stent and expandable withinthe internal circumference of the first stent so as to align the shapedend of the second stent with the opening of the first stent. Thealignment brace when expanded may provide additional support to thefirst stent at or about its opening.

The opening of the first stent may be shaped to complement the shapedend of the second stent upon expansion. In this regard, the shape of theopening of the first stent and the shaped end of the second stent may bebased on the geometries of intersecting cylinders. The length anddiameter of the stents may be selected based on the predetermined shapesof the main and side branches. The first and second stents may intersectat a relative angle of between about 10° and 170°.

The stent apparatus of the invention offers significant and noveladvantages over prior art stents in that the stents of the invention (1)permit precise deployment of the main stent and branched stent in thebifurcated lesions; (2) provide better coverage for the bifurcatedlesions; (3) accommodate different sizing for the main and branchedstents, thus providing better fit; and (4) may be used to treat only themain vessel of the bifurcation lesion, while preserving complete accessto the other branch without ‘stent jail’ of the side branch.

The invention may therefore be used as a double-stent apparatus and asingle-stent apparatus, each of which may be used to cover the origin ofthe bifurcation in a branched vessel. As a single-stent apparatus, theinvention may be used to treat only one branch of the bifurcation whileleaving access to the second branch unobstructed. The invention may beused to provide different sizes and lengths of the branched balloondelivery system and different sizes and lengths of the stents needed tobe delivered in the bifurcated lesions.

The stent apparatus of the present invention is image-able by methodscommonly used during catheterization such as x-ray or ultra-sounds.

These objects and other object advantages and features of the inventionwill become better understood from the detailed description of theinvention and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a perspective view a branched stent in its expandedstate, according to one embodiment of the invention;

FIG. 2 is an exploded perspective view of the branched stent, with theengagement elements highlighted;

FIG. 3 is an elevational view of the main branch stent with the backportion removed for clarity;

FIG. 4A is a side elevational view of the side branch stent according toone embodiment;

FIG. 4B is a top view of the side branch stent shown in FIG. 4A;

FIG. 5 is a schematic representation of a side branched balloonapparatus according to one embodiment of the invention;

FIG. 6 is a schematic representation of a bifurcated vessel and inparticular a side branched bifurcated vessel;

FIGS. 7-16 are schematic representations illustrating the manner inwhich the inflatable balloon apparatus and stent system according to oneaspect of the invention is deployed in a side branched bifurcatedvessel;

FIG. 17A is a side elevational view of an alternate side branch stentaccordingly to an alternate embodiment of the stent system;

FIG. 17B is a top view of the alternate side branch stent shown in FIG.17A;

FIGS. 18-20 are schematic representations illustrating the manner inwhich the inflatable balloon apparatus and alternate stent system isdeployed in a side branched bifurcated vessel;

FIG. 21 is a schematic representation of an alternate deploymentapparatus comprising dual balloons which extend from a sleeve;

FIG. 22 shows the alternate deployment apparatus of FIG. 22 with amodified sleeve; and

FIG. 23 is a perspective view illustrating an alternate embodiment ofthe first balloon of a dual balloon deployment apparatus;

FIGS. 24 to 27 are side views illustrating various alternate embodimentsof the second balloon of a dual balloon deployment apparatus;

FIG. 28 is a side view of a preferred embodiment of the dual balloondeployment apparatus; and

FIG. 29 is a cross-sectional view taken along lines A-A of FIG. 28showing the internal details of the proximal portion of the preferreddual balloon deployment apparatus.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIGS. 1 and 2, an embodiment of a bifurcated stentsystem 10 according to the invention is illustrated. The bifurcatedstent system 10 comprises a generally tubular main stent 12 and agenerally tubular side branch stent 14. The main stent 12 is providedwith a side opening 16 in its cylindrical wall matrix adapted to engageand mate with the proximal end 18 of the side branch stent 14. Ingeneral, when expanded, the side branch stent 14 has an end shape whichcomplements the opening 16 in the main stent 12, which minimizes theover-entanglement of stent wires when the stents have been cooperativelyexpanded, thereby minimizing the potential of obstruction of blood flowat or near the juncture. The opening 16 may be circular, elliptical,diamond-shaped or may closely approximate the intersection of twocylinders at various geometries. Although the side branch stent 14 isshown in FIG. 1 as extending approximately 90° from the main stent 12,the stents 12, 14 may be designed in various shapes and sizes and withvarious geometries to approximate or match the geometry of thebifurcation of the vessels to be treated. For example, the side branchstent 14 shown in FIGS. 4A and 4B are of a slightly smaller diameterthan the main branch stent 12 shown in FIG. 3.

The stents 12, 14 are made using conventional materials and technology.As shown in FIGS. 3, 4A and 4B, the stents 12, 14 may comprise aplurality of adjacent rings 22 which are longitudinally joined byconnectors 24 disposed at selective spaces between adjacent rings 22.Rings 22 generally comprise a plurality of functional units 26consisting of a pair of arms 28, 30 connected by a deformable orbendable joint 32. In the unexpanded state, the arms 28, 30 of stents12, 14 are generally parallel to the longitudinal axes of stents 12, 14.The stents 12, 14 are flexible substantially along their longitudinalaxes when in their unexpanded or constricted state and are relativelymore rigid along their longitudinal axes when expanded. When the stents12, 14 are expanded, joints 32 deform to allow the arms 28, 30 toangularly displace and to thereby allow rings 22 to circumferentiallyexpand in a serpentine manner.

An opening 16 is provided in the side of main stent 12 which is adaptedto be engaged by the shaped end 18 of side branch stent 14 whenexpanded. In this regard, the functional units 36 about the opening 16may be of differing lengths and may be connected differently such as at38 to ensure the opening 16 forms into the appropriate shape when themain stent 12 is expanded and/or to provide additional support at theopening 16. Likewise, the functional units 40 of the end ring 42 thatforms the shaped end 18 of side branch stent 14 may be of varyinglengths to ensure the shaped end 18 forms into the appropriatecomplementary shape when the side branch stent 14 is expanded. As shownin FIGS. 4A and 4B, the end ring 42 has functional units 44 that extendfarthest at the top and bottom (in the orientation shown in FIG. 4A)that engage the parts of the opening 46 which are relatively fartheraway at the top and bottom (in the orientation shown in FIG. 3).

FIG. 5 illustrates an embodiment of the inflatable apparatus 60, alsoknown as a balloon dilatation catheter (shown in its inflated state) fordeploying one or more stents to a bifurcated vessel region according toone embodiment of the invention. The balloon dilatation catheter 60comprises a bifurcated balloon 62 and a pair of catheter lumens 64, 66.The bifurcated balloon 62 comprises a main balloon portion 68 and abranch balloon portion 70. Catheter lumens 64, 66 are provided to allowthe balloon dilatation catheter 60 to be deployed to the bifurcatedvessel region through the use of guide wires 72, 74. Specifically, lumen64 runs through the proximal portion 80 and distal portion 82 of mainballoon portion 68 and accommodates the main branch guide wire 72. Lumen66 accommodates the side branch guide wire 74. The proximal portion 76of lumen 66 runs through the proximal portion 80 of main balloon 68 andthrough the entire branch balloon portion 70, exiting at the distal end84 of branch balloon portion 70. When the terms proximal and distal areused herein, they normally imply relativity to the insertion of thecatheter.

Catheter lumens 64, 66 also provide the means by which the interior ofthe inflatable portions communicate with the supply of gas or fluid forinflation. The supply can be a single source or separate sources may beprovided, which can be controlled unitarily or separately.

Although two separate lumens 64, 66 have been shown, it is envisagedthat a single lumen extending through the balloon catheter may beprovided with a common lumen section in the proximal main balloonportion which bifurcates into a first distal lumen section in the distalportion of the main balloon and a second distal lumen section in thebranch balloon section. It will be understood by those skilled in theart that the guide wires may be part of a rapid exchange wire system orand over the wire exchange system.

FIG. 6 shows a typical bifurcated vessel 90 of the T-type comprising amain vessel 92 and a side branch vessel 94 extending therefrom andhaving plaque or lesions 96 at or about the juncture 98 of the vessels92, 94.

FIGS. 7-16 will be used to illustrate the methodology of accurateplacement of the stent system 10 in the bifurcated vessel 90 using theinflatable deployment apparatus 60 according to one aspect of theinvention. As shown in FIG. 7, guide wires 72, 74 are inserted throughthe proximal portion 100 of main vessel 92. The distal end 104 of mainguide wire 72 is positioned in the distal portion 102 of the main vessel92 while the distal end 106 of the branch guide wire 74 is positioned inthe side branch vessel 94.

As shown in FIG. 8, the inflatable deployment apparatus 60 having themain stent 12 positioned over the main balloon portion 70 is insertedinto the vessel 90 with the bifurcated balloon 62 in a collapsed,unexpanded state. For ease of illustration, the stents 12, 14 are shownschematically without their wire matrix structure. The structure of thestents 12, 14 is such that in their collapsed, unexpanded state, theyare relatively flexible along their longitudinal axes, allowing them tobe delivered through the relatively tortuous paths that comprise thebody's veins and arteries. However, when expanded, stents 12, 14 becomesignificantly rigid and inflexible, allowing them to provide substantialcircumferential support to the vessel walls. The side branch balloon 70extends through the side opening 16 in the main stent 12 and ispositioned in the side branch vessel 94. By sliding the bifurcatedballoon 62 in the collapsed state over the placed guide wires 72, 74,with the main stent 12 over the main balloon 68, the main stent 12 willbe positioned accurately in the main vessel 92, with side opening 16 ofthe main stent 10 is positioned accurately at the juncture 98 of theside branch vessel 94 on account of the registration of the side branchballoon 70 within branch vessel 94.

As shown in FIG. 9, the bifurcated balloon 62 is expanded, causing mainstent 12 to circumferentially expand. The side opening 16 maintains goodregistration with the juncture 98 of the side branch vessel 94 due tothe expansion of the side branch balloon portion 70. The bifurcatedballoon 62 is then deflated as shown in FIG. 10, leaving the main stent12 in accurate position within the main vessel 92. The inflatabledeployment apparatus 60 with deflated bifurcated balloon 62 is thenwithdrawn from the bifurcated vessel 90 leaving the guide wires 72, 74in place as shown in FIG. 11.

In reference to FIG. 12, there is illustrated the deployment of the sidebranch stent 14, which has been arranged on the side branch balloonportion 70 of a bifurcated balloon 62, with the side branch stent 14positioned such that its shaped end 18 will be in appropriate alignmentwith the opening 16 of the main stent 12 when expanded. The inflatabledeployment apparatus 60 is repositioned using guide wires 72, 74 intothe bifurcated vessel 90 as explained previously. The bifurcated balloon62 is then inflated as shown in FIG. 13, thereby causing side branchstent 14 to circumferentially expand about inflating side branch balloonportion 70. As the stents 12, 14 are precisely positioned, the end 18 ofthe side branch stent 14 engages precisely within the opening 16 of themain stent 12 at the junction 98, forming a relatively clean, minimallyintrusive, intersection 108 therebetween due to the complementaryshapes.

The bifurcated balloon 62 is then deflated as shown in FIG. 14 and theinflatable deployment apparatus 60 withdrawn as shown in FIG. 15. Theguide wires 72, 74 are then withdrawn as shown in FIG. 16, leaving thebifurcated stent system 10 accurately placed in the bifurcated vessel90.

An alternate embodiment of the bifurcated stent system is shown in FIGS.17A and 17B. More particularly, the alternate bifurcated stent systemcomprises a modified branch stent 114, similar to branch stent 14, buthaving an alignment brace 120 extending from the shaped proximal end118. The alignment brace 120 is generally semicircular in the transversedirection (transverse to the longitudinal axis of the branch stent) asshown in FIG. 17A. The modified branch stent 114 is designed to pairwith a main branch stent 112 (not shown in FIGS. 17A-B) which isgenerally identical with the main stent 12 of the stent system 10. Thepurpose of the alignment brace 120 is to permit more assured alignmentof the modified branch stent 114 with the main branch stent 112, andmore particularly, more accurate positioning of the shaped end 118 ofthe modified branch stent 114 with the complementary opening 116 of themain branch stent 112, as will be seen in FIGS. 18-20.

The alignment brace 120 is attached to the extended functional units 144of the shaped end 118 at deformable joints 124 to thereby form agenerally tubular transverse opening 126 which, when expanded, isadapted to approximate the internal circumference of the main stent.

FIGS. 18-20 show, in part, the methodology of accurate placement of thealternate stent system 110 in a bifurcated vessel 90 according to analternate aspect of the invention using the inflatable deploymentapparatus 60. FIG. 18 shows the main stent 112 already deployed in thebifurcated vessel 90. The deployment of the main stent 112 is the sameas the deployment of main stent 12 described above in connection withFIGS. 6-11. The main stent 112 is shown schematically in cross-sectionin FIGS. 18-20 (i.e. only the rear half showing) to better illustratethe operation of the alignment brace 120.

In reference to FIG. 18, there is illustrated the deployment of themodified side branch stent 114, which has been arranged on the sidebranch balloon portion 70 of the bifurcated balloon 62, with the mainbranch balloon portion 68 positioned though the alignment brace 120. Asmentioned above, the alignment brace 120 is attached to the side branchstent 114 by deformable joints 124. This allows the alignment brace 120to bend relative to the longitudinal axis of the side branch stent 114so as to permit the side branch balloon portion 70 to be parallel withthe main balloon portion 68 for insertion purposes and to permit bendingback into alignment with the longitudinal axis of the side branch stent114 when the inflatable deployment apparatus 60 reaches the bifurcationwith branch balloon 70 extending into the side branch 94 as shown inFIG. 18. The arrangement of the alignment brace 120 over the mainballoon 68 permits highly accurate positioning of the side branch stent114 so as to guarantee that the shaped end 118 will align precisely withthe opening 116 in the main stent 114. In this regard, as shown in FIG.19, the bifurcated balloon 62 is inflated, causing the side branch stent114 to circumferentially expand in the branch vessel 94 about the branchballoon 70 and to simultaneously expand alignment brace 120 about theexpanding main balloon 68 within the main stent 112. The expandingalignment brace 120 maintains the orientation of the shaped end 118 withthe expanding opening 116 of the main stent to better ensure accurateengagement therebetween upon full expansion. The alignment brace 120also minimizes the potential for gaps or overlap which can occur at theintersection 128 when there is no such means for maintaining theregistration of the opening 116 and end shape 118 of the stents 112,114. A better intersection with potentially less gaps or overlapstherebetween will promote better dynamic fluid flow and thereby reducefluid turbulence, which will result in a reduction in the possibility ofstenosis of the stent by blood products.

The expanded alignment brace 120 also provides additional bracingsupport of the internal wall of main stent 114, particularly around thearea of the opening 116 where the main stent 114 will be least rigid.

The bifurcated balloon 60 is then deflated and withdrawn along with theguide wires 72, 74 as shown in FIG. 20, leaving the modified bifurcatedstent system 110 accurately placed in the bifurcated vessel 90.

Besides constructing the inflatable balloon apparatus with a unitaryinflatable balloon as shown in FIG. 5, it is also possible to constructit with using a pair of balloons. The difficulty in using two balloonsat a T-shaped bifurcated vessel is the balloons have to overlap in oneside of the main branch. When expanded, this causes the overlappingballoon portions to expand more than the portion of the balloon in theother side of the main branch, resulting in uneven circumferentialexpansion of the stent in the main branch. To overcome this problem, arestrictive member, such as a sleeve, may be positioned around theportions of the balloons which overlap. In this regard, there is shownin FIG. 21 an alternative embodiment to the unitary inflatable balloon62. A dual balloon deployment apparatus 200 comprises a first balloon202 and a second balloon 204 which are encased in a sleeve 206 at theirproximal ends 208, 210 which overlap. The balloons 202, 204 may besupplied with an inflatable gas or liquid from a common source so as tobe inflatable and deflatable in unison. The sleeve 202 is designed torestrict the expansion of the proximal ends 208, 210 of balloons 202,204 to the same extent as the expansion of the distal end 212 of thefirst balloon 202. The distal end 214 of the second balloon 204 extendsfrom the sleeve opening 216 at a region between the proximal and distalends 208, 212 of the first balloon. The main branch and side branchstents (not shown) are disposed on the deployment apparatus 200 in thesame manner as the inflatable apparatus 60, with the main stent spanningthe sleeved proximal ends 208, 210 of the first and second balloons 202,204 and the distal end 212 of the first balloon 202, and with the distalend 214 of the second balloon 204 extending through the opening of themain stent. In this manner, the main stent may be expanded uniformly asthe first and second balloons 202, 204 are expanded.

In construction of the dual balloon deployment apparatus 200, using thesleeve 206, an adhesive process or technology is required, to assure thebonding of the fabrics materials from which the balloons 202, 204 aremade. In this embodiment, lamination processes were used to secure theattachment of all materials to each other. After lamination is achieved,the balloon sleeve 206 and the first and second balloons 202, 204 willbehave as one unit. In this regard, the sleeve 206 will expand andcollapse, upon the inflation and deflation of the balloons 202, 204.

To provide additional support at the sleeve opening 216, an optionalsupport band 218 may be provided to prevent the sleeve 210 from tearingupon inflation. The support band 200 may be attached to the sleeve 210by a lamination process to secure the bonding of the fabrics materials.

To provide better angular support for the distal end 212 of the second(side branch) balloon 204, a longer sleeve 222 as shown in FIG. 22 maybe provided which includes an opening 224 through which the distal end212 of the second balloon 204 exits. The longer sleeve 222 may also beprovided with the optional sleeve 218 for greater support near theproximal side of opening 224.

An alternate embodiment of the first balloon in its expanded state isshown at 242 in FIG. 23 in which there is provided a longitudinal groove242 that extends along the proximal end portion 248 to about themidpoint or a point 246 between the proximal end 248 and distal end 252where the distal end of the second balloon (not shown in FIG. 23) isadapted to extend. The groove 244 helps reduce any over-expansion of theproximal ends of the balloons within the sleeve and, hence,over-stretching of the vessel walls during expansion.

Embodiments of the second balloon are shown in FIGS. 24 to 27. FIG. 24shows a second balloon 264 as having a uniform tubular shape withsubstantially equal-sized proximal 268 and distal 272 ends. To help easethe stress at the bending point, another embodiment of the secondballoon 274 is formed with an angular bend 276, as shown in FIG. 25,between the proximal 278 and distal 282 ends. The reduction in stressmay also lessen the propensity of tearing of the sleeve duringinflation. In FIG. 26, there is shown at 284 an alternate embodiment ofthe second balloon of FIG. 25, wherein a reverse bend 286 is providedbetween the proximal 288 and distal 292 ends. The reverse bend 286allows the distal end 292 of the second balloon 284 to remainsubstantially parallel to the first balloon (not shown) for ease ofinsertion.

Another modification in the shape of the side branch second balloon ofFIG. 26 is shown in FIG. 27. In this embodiment, the second balloon 294is provided with a proximal end 298 which is of reduced diameterrelative to the diameter of the distal end portion 296. Again theadvantage of reducing the diameter size of the proximal 298 portion ofthe side branch second balloon 294 is that it will help reduce stress onthe sleeve, as well as the possible over-expansion of the stent and theassociated overstretching of the vessel during the full inflation ofboth balloons inside the balloon sleeve.

In FIG. 28, there is shown a preferred embodiment of a dual balloondeployment apparatus 300 comprising the grooved first balloon embodiment242 as shown in FIG. 23 with the second balloon embodiment 294 as shownin FIG. 26, and sleeve 222 as shown in FIG. 22. The reduced diameterproximal end portion 298 of the second balloon 294 seats within groove244 in the proximal end portion 248 of the first balloon 242 as can bebest seen in cross-section in FIG. 29. Sleeve 222 surrounds the proximalend portions 248,298 of the first and second balloons 242, 294 andextends along a section 302 of the distal end portion 252 of the firstballoon 242. The distal end portion 296 of the second balloon 294extends through the sleeve opening 216. The proximal end portions 248,298 of the first and second balloons 242, 294 and the distal end portion252 of the first balloon 242 forms a primary inflatable portion forexpanding the main stent in the main vessel while the distal end portion296 of the second balloon 294 maintains registration with the sidebranch vessel and may subsequently be used to expand a side branch stentinto the side branch vessel.

Although there have been shown various embodiments and examples of theinflatable deployment apparatuses, the bifurcated stent systems andmethods of deploying stents at bifurcated lesions, it will beappreciated by those skilled in the art that these embodiments andexamples should not be considered limiting and that variousmodifications and substitutions may be made to the inventions defined inthe appended claims without departing from the spirit and scope of theinvention.

1. A method for deployment of at least one stent in a bifurcated vesselhaving a main branch from which a side branch extends therefrom,comprising the steps of: providing an inflatable apparatus having aprimary inflatable portion and a secondary inflatable portion; arranginga first stent on said primary inflatable portion; deploying saidinflatable apparatus to said bifurcated vessel and positioning saidprimary inflatable portion in said main branch and said secondaryinflatable portion in said side branch; inflating said primary and saidsecondary inflatable portions so as to cause said first stent toradially expand within said main branch while said secondary inflatableportion maintains registration with said side branch.
 2. The method ofclaim 1, further comprising the step of positioning said secondaryinflatable portion through an opening in said first stent when arrangingsaid first stent on said primary inflatable portion.
 3. The method ofclaim 2, further comprising the steps of: removing said inflatableapparatus once said first stent has been expanded; arranging a secondstent on said secondary inflatable portion; redeploying said inflatableapparatus by positioning said primary inflation portion within saidexpanded first stent and positioning said secondary inflatable apparatusin said side branch; inflating said primary and said secondaryinflatable portions causing said second stent to expand radially withinsaid side branch while said primary inflatable portion maintainsregistration with said main branch.
 4. The method of claim 3, whereinsaid second stent further comprises alignment means for orienting aproximal end of said second stent with an opening of said first stent.5. The method of claim 4, wherein said alignment means comprises anexpandable alignment brace extending from said proximal end of saidsecond stent, said alignment brace being adapted to have said primaryinflatable portion extend therethrough, so that when said primary andsecondary inflatable portions are inflated, said primary inflatableportion expands said alignment brace within an internal circumference ofsaid first stent and aligns a shaped end of said second stent with saidopening of said first stent.
 6. The method of claim 1, wherein saidinflatable apparatus further comprises: a first balloon and a secondballoon each having proximal and distal ends; a sleeve surrounding saidproximal ends of both balloons; said distal end of said second balloonforming said secondary inflatable portion; sleeve-surrounded proximalends of said balloons and said distal end of said first balloon formingsaid primary inflatable portion.